1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/layout/generic/nsColumnSetFrame.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,221 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +/* rendering object for css3 multi-column layout */
1.10 +
1.11 +#include "mozilla/Attributes.h"
1.12 +#include "nsContainerFrame.h"
1.13 +
1.14 +class nsColumnSetFrame : public nsContainerFrame {
1.15 +public:
1.16 + NS_DECL_FRAMEARENA_HELPERS
1.17 +
1.18 + nsColumnSetFrame(nsStyleContext* aContext);
1.19 +
1.20 + virtual nsresult SetInitialChildList(ChildListID aListID,
1.21 + nsFrameList& aChildList) MOZ_OVERRIDE;
1.22 +
1.23 + virtual nsresult Reflow(nsPresContext* aPresContext,
1.24 + nsHTMLReflowMetrics& aDesiredSize,
1.25 + const nsHTMLReflowState& aReflowState,
1.26 + nsReflowStatus& aStatus) MOZ_OVERRIDE;
1.27 +
1.28 + virtual nsresult AppendFrames(ChildListID aListID,
1.29 + nsFrameList& aFrameList) MOZ_OVERRIDE;
1.30 + virtual nsresult InsertFrames(ChildListID aListID,
1.31 + nsIFrame* aPrevFrame,
1.32 + nsFrameList& aFrameList) MOZ_OVERRIDE;
1.33 + virtual nsresult RemoveFrame(ChildListID aListID,
1.34 + nsIFrame* aOldFrame) MOZ_OVERRIDE;
1.35 +
1.36 + virtual nscoord GetMinWidth(nsRenderingContext *aRenderingContext) MOZ_OVERRIDE;
1.37 + virtual nscoord GetPrefWidth(nsRenderingContext *aRenderingContext) MOZ_OVERRIDE;
1.38 +
1.39 + /**
1.40 + * Retrieve the available height for content of this frame. The available content
1.41 + * height is the available height for the frame, minus borders and padding.
1.42 + */
1.43 + virtual nscoord GetAvailableContentHeight(const nsHTMLReflowState& aReflowState);
1.44 +
1.45 + virtual nsIFrame* GetContentInsertionFrame() MOZ_OVERRIDE {
1.46 + nsIFrame* frame = GetFirstPrincipalChild();
1.47 +
1.48 + // if no children return nullptr
1.49 + if (!frame)
1.50 + return nullptr;
1.51 +
1.52 + return frame->GetContentInsertionFrame();
1.53 + }
1.54 +
1.55 + virtual nsresult StealFrame(nsIFrame* aChild, bool aForceNormal) MOZ_OVERRIDE
1.56 + { // nsColumnSetFrame keeps overflow containers in main child list
1.57 + return nsContainerFrame::StealFrame(aChild, true);
1.58 + }
1.59 +
1.60 + virtual bool IsFrameOfType(uint32_t aFlags) const MOZ_OVERRIDE
1.61 + {
1.62 + return nsContainerFrame::IsFrameOfType(aFlags &
1.63 + ~(nsIFrame::eCanContainOverflowContainers));
1.64 + }
1.65 +
1.66 + virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder,
1.67 + const nsRect& aDirtyRect,
1.68 + const nsDisplayListSet& aLists) MOZ_OVERRIDE;
1.69 +
1.70 + virtual nsIAtom* GetType() const MOZ_OVERRIDE;
1.71 +
1.72 + virtual void PaintColumnRule(nsRenderingContext* aCtx,
1.73 + const nsRect& aDirtyRect,
1.74 + const nsPoint& aPt);
1.75 +
1.76 +#ifdef DEBUG_FRAME_DUMP
1.77 + virtual nsresult GetFrameName(nsAString& aResult) const MOZ_OVERRIDE {
1.78 + return MakeFrameName(NS_LITERAL_STRING("ColumnSet"), aResult);
1.79 + }
1.80 +#endif
1.81 +
1.82 +protected:
1.83 + nscoord mLastBalanceHeight;
1.84 + nsReflowStatus mLastFrameStatus;
1.85 +
1.86 + /**
1.87 + * These are the parameters that control the layout of columns.
1.88 + */
1.89 + struct ReflowConfig {
1.90 + // The number of columns that we want to balance across. If we're not
1.91 + // balancing, this will be set to INT32_MAX.
1.92 + int32_t mBalanceColCount;
1.93 +
1.94 + // The width of each individual column.
1.95 + nscoord mColWidth;
1.96 +
1.97 + // The amount of width that is expected to be left over after all the
1.98 + // columns and column gaps are laid out.
1.99 + nscoord mExpectedWidthLeftOver;
1.100 +
1.101 + // The width of each column gap.
1.102 + nscoord mColGap;
1.103 +
1.104 + // The maximum height of any individual column during a reflow iteration.
1.105 + // This parameter is set during each iteration of the binary search for
1.106 + // the best column height.
1.107 + nscoord mColMaxHeight;
1.108 +
1.109 + // A boolean controlling whether or not we are balancing. This should be
1.110 + // equivalent to mBalanceColCount == INT32_MAX.
1.111 + bool mIsBalancing;
1.112 +
1.113 + // The last known column height that was 'feasible'. A column height is
1.114 + // feasible if all child content fits within the specified height.
1.115 + nscoord mKnownFeasibleHeight;
1.116 +
1.117 + // The last known height that was 'infeasible'. A column height is
1.118 + // infeasible if not all child content fits within the specified height.
1.119 + nscoord mKnownInfeasibleHeight;
1.120 +
1.121 + // Height of the column set frame
1.122 + nscoord mComputedHeight;
1.123 +
1.124 + // The height "consumed" by previous-in-flows.
1.125 + // The computed height should be equal to the height of the element (i.e.
1.126 + // the computed height itself) plus the consumed height.
1.127 + nscoord mConsumedHeight;
1.128 + };
1.129 +
1.130 + /**
1.131 + * Some data that is better calculated during reflow
1.132 + */
1.133 + struct ColumnBalanceData {
1.134 + // The maximum "content height" of any column
1.135 + nscoord mMaxHeight;
1.136 + // The sum of the "content heights" for all columns
1.137 + nscoord mSumHeight;
1.138 + // The "content height" of the last column
1.139 + nscoord mLastHeight;
1.140 + // The maximum "content height" of all columns that overflowed
1.141 + // their available height
1.142 + nscoord mMaxOverflowingHeight;
1.143 + // This flag determines whether the last reflow of children exceeded the
1.144 + // computed height of the column set frame. If so, we set the height to
1.145 + // this maximum allowable height, and continue reflow without balancing.
1.146 + bool mHasExcessHeight;
1.147 +
1.148 + void Reset() {
1.149 + mMaxHeight = mSumHeight = mLastHeight = mMaxOverflowingHeight = 0;
1.150 + mHasExcessHeight = false;
1.151 + }
1.152 + };
1.153 +
1.154 + /**
1.155 + * Similar to nsBlockFrame::DrainOverflowLines. Locate any columns not
1.156 + * handled by our prev-in-flow, and any columns sitting on our own
1.157 + * overflow list, and put them in our primary child list for reflowing.
1.158 + */
1.159 + void DrainOverflowColumns();
1.160 +
1.161 + bool ReflowColumns(nsHTMLReflowMetrics& aDesiredSize,
1.162 + const nsHTMLReflowState& aReflowState,
1.163 + nsReflowStatus& aReflowStatus,
1.164 + ReflowConfig& aConfig,
1.165 + bool aLastColumnUnbounded,
1.166 + nsCollapsingMargin* aCarriedOutBottomMargin,
1.167 + ColumnBalanceData& aColData);
1.168 +
1.169 + /**
1.170 + * The basic reflow strategy is to call this function repeatedly to
1.171 + * obtain specific parameters that determine the layout of the
1.172 + * columns. This function will compute those parameters from the CSS
1.173 + * style. This function will also be responsible for implementing
1.174 + * the state machine that controls column balancing.
1.175 + */
1.176 + ReflowConfig ChooseColumnStrategy(const nsHTMLReflowState& aReflowState,
1.177 + bool aForceAuto, nscoord aFeasibleHeight,
1.178 + nscoord aInfeasibleHeight);
1.179 +
1.180 + /**
1.181 + * Perform the binary search for the best balance height for this column set.
1.182 + *
1.183 + * @param aReflowState The input parameters for the current reflow iteration.
1.184 + * @param aPresContext The presentation context in which the current reflow
1.185 + * iteration is occurring.
1.186 + * @param aConfig The ReflowConfig object associated with this column set
1.187 + * frame, generated by ChooseColumnStrategy().
1.188 + * @param aColData A data structure used to keep track of data needed between
1.189 + * successive iterations of the balancing process.
1.190 + * @param aDesiredSize The final output size of the column set frame (output
1.191 + * of reflow procedure).
1.192 + * @param aOutMargin The bottom margin of the column set frame that may be
1.193 + * carried out from reflow (and thus collapsed).
1.194 + * @param aUnboundedLastColumn A boolean value indicating that the last column
1.195 + * can be of any height. Used during the first iteration of the
1.196 + * balancing procedure to measure the height of all content in
1.197 + * descendant frames of the column set.
1.198 + * @param aRunWasFeasible An input/output parameter indicating whether or not
1.199 + * the last iteration of the balancing loop was a feasible height to
1.200 + * fit all content from descendant frames.
1.201 + * @param aStatus A final reflow status of the column set frame, passed in as
1.202 + * an output parameter.
1.203 + */
1.204 + void FindBestBalanceHeight(const nsHTMLReflowState& aReflowState,
1.205 + nsPresContext* aPresContext,
1.206 + ReflowConfig& aConfig,
1.207 + ColumnBalanceData& aColData,
1.208 + nsHTMLReflowMetrics& aDesiredSize,
1.209 + nsCollapsingMargin& aOutMargin,
1.210 + bool& aUnboundedLastColumn,
1.211 + bool& aRunWasFeasible,
1.212 + nsReflowStatus& aStatus);
1.213 + /**
1.214 + * Reflow column children. Returns true iff the content that was reflowed
1.215 + * fit into the mColMaxHeight.
1.216 + */
1.217 + bool ReflowChildren(nsHTMLReflowMetrics& aDesiredSize,
1.218 + const nsHTMLReflowState& aReflowState,
1.219 + nsReflowStatus& aStatus,
1.220 + const ReflowConfig& aConfig,
1.221 + bool aLastColumnUnbounded,
1.222 + nsCollapsingMargin* aCarriedOutBottomMargin,
1.223 + ColumnBalanceData& aColData);
1.224 +};
